1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.math.fraction;
19
20 import java.io.Serializable;
21
22 import org.apache.commons.math.Field;
23
24 /**
25 * Representation of the fractional numbers without any overflow field.
26 * <p>
27 * This class is a singleton.
28 * </p>
29 * @see Fraction
30 * @version $Revision: 795908 $ $Date: 2009-07-20 12:42:55 -0400 (Mon, 20 Jul 2009) $
31 * @since 2.0
32 */
33 public class BigFractionField implements Field<BigFraction>, Serializable {
34
35 /** Serializable version identifier */
36 private static final long serialVersionUID = -1699294557189741703L;
37
38 /** Private constructor for the singleton.
39 */
40 private BigFractionField() {
41 }
42
43 /** Get the unique instance.
44 * @return the unique instance
45 */
46 public static BigFractionField getInstance() {
47 return LazyHolder.INSTANCE;
48 }
49
50 /** {@inheritDoc} */
51 public BigFraction getOne() {
52 return BigFraction.ONE;
53 }
54
55 /** {@inheritDoc} */
56 public BigFraction getZero() {
57 return BigFraction.ZERO;
58 }
59
60 /** Holder for the instance.
61 * <p>We use here the Initialization On Demand Holder Idiom.</p>
62 */
63 private static class LazyHolder {
64 /** Cached field instance. */
65 private static final BigFractionField INSTANCE = new BigFractionField();
66 }
67
68 /** Handle deserialization of the singleton.
69 * @return the singleton instance
70 */
71 private Object readResolve() {
72 // return the singleton instance
73 return LazyHolder.INSTANCE;
74 }
75
76 }